1. Field of the Invention
The invention relates to a vehicular drive apparatus and, more particularly, to a technology for providing the drive apparatus with an integrated electronic circuit for controlling the drive apparatus.
2. Description of Related Art
A drive apparatus installed in a vehicle needs an electronic control unit for controlling a fuel supply system for the engine and a speed shift mechanism of the automatic transmission if the drive apparatus is a combination of a combustion engine (referred to as “engine” in this specification) and an automatic transmission. In the case of a hybrid drive apparatus that incorporates an engine and an electric motor (a motor or a motor-generator) as drive power sources, and that employs a transfer apparatus combined with the drive power sources, the drive apparatus needs a power unit and an electronic control unit for controlling a fuel supply system for the engine and a power line for the electric motor.
Conventionally, it is normal to dispose an electronic control unit and a power unit as mentioned above at locations in a compartment of a vehicle which have good thermal and vibrational conditions because these circuits incorporate chips that are susceptible to heat and vibrations.
In normal cases, since the electronic circuits of the electronic control unit and the power unit are not disposed at locations exposed to sever vibrations as mentioned above, there is no need to consider such vibrational conditions in disposing and arranging the electronic circuits. However, modules are now being used for the purpose of size and cost reduction. Along with this trend, it is conceived to mount an electronic circuit in an engine room, directly on an engine or indirectly from the engine via an accessory or the like. In this case, the electronic circuit is placed under a harsh condition where the circuit directly receives vibrations from the engine. Therefore, there are many problems related to resistances against such conditions. With regard to the thermal resistances of circuit materials of a module and chips embedded therein, some improvements have been made based on contrivances in cooling means. However, improvement in vibration resistance of a module as a whole is difficult. Thus, this technical idea has not been developed to a level of practical use.